How-To: FCR carburetor accelerator pump timing adjustment

[@heathgraham4911]

probably one of the most informative and easy to understand creators I have watched

[@kemitchell]

This was very, very good. Taking the time to show over, under, and well adjusted, both from the mechanic's point of view and in action, is gold.

[@HTMR]

Thanks Kyle!

[@jarrettdidawick7309]

You are literally the only person that makes sense on this topic, I have a crf150r and I had problems with bog and I tried everything. Just until I found this, I tried and it my bike runs 110% better. Thank you dude. Really thank you

[@HTMR]

Glad it helped.

[@Espenrip]

You made my day awesome today. First YT video i opened. Answered my question instantly. THANK YOU SIR. Coz i just bought an old YZ250 ‘06. My very first dirtbike. My 11yo race on his 65cc ktm. 3 yrs now, I fast paced learn how to fix and maintain this lil ripper. I dont have a deep pocket, so we have to rely on diy. Now i got me a dirtbike so i dont have to watch him ride anymore. I tore down this yz already twice, to clean and learn the bike inside out. I noticed this o-ring wrap around that accl pump adjuster. And YOU sir just gave the answer. THANK YOU VERY MUCH FOR THE DETAILED EXPLANATIONS in regards to this part of the carb. Your lessons are priceless. Buying you a dozen of beerz still priceless. Have a great day.

[@thatsnotatraxxas5230]

Bro I was fighting my 05 yfz for hours before watching this video. You are the man thank you so damn much.

[@carlosbarragan6729]

You deserve an award for humanitarian aid. Thanks again

[@vformarallo]

Two years later and you are still helping motorcycles, my scooter now accelerates a bit better thanks to you haha cheers

[@jessea6959]

Thanks Matt. My 2004 wr250f has always had a terrible bog in the throttle. After watching your video and following your steps and adding the o-ring it has made a huge difference!!!!

[@HTMR]

No problem. If you are looking for an even bigger difference, throw a smaller leak in there.

[@popdizzleutah]

Thank you! I had the o-ring on but I jumped to a QuickShot, JD kit and different jets, trying to get the bog worked out. After watching your video, turns out that screw was so far out, I was only getting 1/2 a shot of fuel. I adjusted that and got immediate results. The QS, JD and jets did absolutely nothing when I adjusted them. I have a Rekluse auto-clutch and the bike is idling low. I turned up the idle and that contributed to it being much snappier as well. I believe a Rekluse can magnify the bog problem. Thanks for taking time to post this.

[@HTMR]

Your welcome!

[@1991enduro]

Y a auto clutch man u yankys man its all in the clutch mate trust me i rekon its cheating definatly in enduro clutch for me on anything car n bike

[@That119compact]

You are the man, between this video and the fuel screw video I was able to dial in both my 450r and my wife's 150r. THANK YOU!

[@HTMR]

No prob!

[@endurolifecom]

My old Husaberg FE450 liked this.

[@myran_moto330]

Im doing this on my gf's husaberg right now😇

[@nuwaveband869]

@@myran_moto330 y

[@calebmacgray4588]

Thank you so much for this. AP pump timing has always been gypsy magic to me and I've been living with the Honda bog for ages. No one really has a good video of this until now so thank you lol

[@HTMR]

No problem. I hope I simplified how to set it up.

[@jrich240h]

@@HTMR Hi Matt. What if you have inline 4 carbs and carbs 2, 3, and 4 squirt gas when you actuate throttle, but carb 1 doesn't? Keihein carbs on an 82 honda 650 nighthawk. Issue with accelerator pump? Or perhaps a clog somewhere?

[@HTMR]

@@jrich240h Nozzle is probably clogged.

[@pufifa]

Yes! I was about to ask, what happens if I set up the carb as shown in this video, but my idle is not setup.... I have carb off the bike atm... This was super informative! Many thanks for sharing this!

[@eliwesson2970]

Just want to say thanks for these awesome instructional videos I appreciate your work 🙏

[@benjaminengle183]

My guy. You saved me and this headache. Thank you for the great video.

[@breitenbachmotorsports6120]

Ur the only one who helped me

[@neil4634]

This is a perfect instructional video for setting up the Keihin AP. Thank you!

[@MasonCleveland]

I was having crazy bad bogging issues on my 11 ktm 530. Managed to adjust the slop out of the ap using the adjustment screw. Had to look carefully at where the rod that presses the diaphragm sits in the black plastic arm. You can see the slop and find where it is no longer pressing the rod down at all. Absolutely rips now no bog from idle while riding. I am also using the thick o ring from the JD jet kit. Worked great for me without removing the carb from the bike. Only the seat and gas tank.

[@scoooby14]

Thanks a lot mate, you deserve a billion likes.

[@HTMR]

Thanks!

[@j.d.7321]

Thanks man, I'm a novice to carburetors and that was well explained.

[@justinlandrey7659]

I did this with an 06 crf250r I bought for nothing , none one could get rid of the bog . worked 100percent . bog gone runs like a beauty , great video thanks .

[@jordanboulding7299]

Fixed my bike so happy thanks mate

[@GiantMX]

thank you! i just rebuilt a crf250 and this was the one thing keeping it from starting properly. went from 50 kicks to 1 with one small adjustment!

[@John_Doe_6996]

I recently bought an 05 crf 250r, hard to start as well, but runs good, checked valves, they're in spec, spark plug and air filter look good, next is re-jetting, and I suppose I'll check my accelerator pump as well...Didnt know that could be out of adjustment...(my first dirtbike) wish me luck...

[@GiantMX]

@@John_Doe_6996 good luck! just an fyi now that mine is broken in, i had to do another valve adjustment. everything has to be perfect on these motors for them to start easy appearantly. but at least they'll run forever haha! p.s. try a smooth kick from top dead center instead of giving it all you got. seems to like that better

[@fredriksalmen5159]

Thanks for great video! One question, you say squirt time should be 0.8-1 sec, but in you video it's about 0.4 when you say it looks good, so what should I aim for?

[@evanlebaron9465]

I subbed! Great video, I wish every video was as on point as this one

[@JD-pt1ij]

Thanks man. I definitely learned a lot on these types of carburetors. Since i was used to bikes with no AP's Thumbs up man

[@Espenrip]

Thanks!

[@vboy1212]

FROM DA BIG ISLAND THANK U SO MUCH YOUR VIDEO HELPED ME SOLVE MY PROBLEM I HAVE A 05YZ250F AND WAS REALLY WAS HAVING A REALLY BAD BOG NOW BIKE IS MINT GOD BLESS AND MAHALO AGAIN😉😎🍒🤙

[@wilcovos2706]

THANK YOU! This is the only vid i can find that explains verry clearly how to adjust the accelerator pump! My bike runs perfect now✊😀.

[@amandagregg2195]

How do you adjust accelerator pump I am rebuilding carb bike starting without choke

[@wilcovos2706]

@@amandagregg2195 take the black plastic cover of that is on the right side of the carb. And then just turn the adjuster screw to when there is almost no play in the arm. ( the guy in the vid made it more clear then i can do, sorry😅)

[@ryandiogo2051]

This is an awesome video! The temp fuel setup to show the fuel delivery difference is great. Thank you.

[@eldongee]

Thank u. My Wr400f is happier now. And so am I

[@ottovp]

THANK YOU SO FUCKIN MUCH!!!! this is a ****** MASTERPIECE!!!! i tried almost every place on earth to calibrate my accelerator pump but nowhere was this clear as this vid!!! MAD PROPS TO YOU MATE!

[@HTMR]

Your f***in welcome :)

[@boystoyz8922]

Just cleaned one of these, for my kx250f. Complete teardown and ultrasonic cleaning. Everything seems good but I have alot of backfire win I get into 3/4 -full throttle and let off. Is that my main jet to big or is it float bowl level. Had a hard time adjusting the float.

[@HTMR]

When you let off, you are back on the pilot circuit. Tune your pilot jet and fuel screw per this video: kzbin.info/www/bejne/oYbaZWSpiraVirs

[@c4r5on88]

I'm having to remove my carb to find out why my plastic black idol screw won't turn and while it's off in definitely going to be looking at and doing it if it's not already set up. Thank you

[@TheGamersRace]

Wish my Mikuni TM33 had some apump adjustments on it. Quick opening the throttle like you did has a stutter, and then acceleration kicks in. I'll have to look it over.

[@kw3640]

What size main jet and pilot jet would u recomend? Great video thank u!

[@danielreinhardt937]

Carbs are tricky. Thanks for the help.

[@juddbelue1283]

Bravo Matt…Another classic!

[@GeneralDakine]

Very clear instructional video thanks. I'm looking to upgrade my z400 stock carb that's jetted to a fcr style currently running a 170 main and 75 low jets with a Yoshi pipe and stainless header she does good now but I want little more for the hole shot

[@jaredc5789]

I tried finding a #78 o-ring and for some reason danco uses weird numbers. For those of you looking a #108 o-ring is the number most manufacturers use it's 1/4 i.d. 3/32 cross section 7/16 o.d. do you know if you can use a #202? Which would be 1/4" I.d. 1/8" cross section 1/2" o.d. if it fits it should last longer?

[@arkbama6]

This is hands down the best video on getting the accelerator pump tweaked for maximum performance. Getting that “play” - “slop” is the key! And the Oring is a must. I would also recommend the shorter post diaphragm and smaller leak jet. My crf250r acts like it’s fuel injected.

[@HTMR]

Yes, I always use a 45 leak. Haven't had to tweak the posts as of yet.

[@arkbama6]

The kits are available at CRF Only website along with instructions. I prematurely ruined the original on my Accelerator pump with carb cleaner😏. Found the CRF Only kits to be a good buy. I’ve picked up two over the years.

[@whitefish79]

Great video on a much overlooked topic. Thanks, man. Good work!

[@HTMR]

Thanks!

[@RoderickSquadDMcCloud]

Awesome! Definitely needed this video! Running into this problem with the yz450f at the moment…

[@HorsepowerHouse]

This is a commonly overlooked thing on a modern 4-stroke mx bike with the Keihin FCR-MX Carb. Pretty much all common bike brands use a version of this carb if it's a 4-stroke high performance bike. Very easy thing to check and will minimize if not eliminate any off-idle hesitation or bog. Highly recommend ALL of you to do this inspection. (this as well as clean your dang carb every once in a while - and inspect your pilot jet for blockage - AND never never never use standard ethanol-based pump gas. (Because it can clog your pilot jet over time.)

[@bikersoncall]

Where do you get non ethanol fuel?

[@fierce1894]

@@bikersoncall yeah exactly that's the problem 😂

[@sbz666_]

@@bikersoncall If you're somewhere that doesn't sell non-ethanol fuel, your best bet is VP T4 Fuel. It's 97 octane ethanol-free fuel for stock or slightly modified engines. It's expensive as hell at $110 for 5gal but it's an option if you really don't want corn in your bike.

[@johnadamo4402]

The o ring hack did the trick!!! Thanks man!

[@bradroute3998]

This is a great video and I love watching your expertise. I have a 07 yz250f and as soon as I did the o-ring mod it started bogging badly. I took the carb off and my ap arm has no slop in it without the throttle cable rigged up whether it's screwed all the way in or not. Should I just set the timing after it has the tension from the throttle cables?

[@HTMR]

Set the timing after idle has been adjusted. Oring must be removed for this.

[@bradroute3998]

@@HTMR thank you for your reply!

[@swemx7403]

Okey so i've done what you did in this video (back in september). I setup the squirt just perfect with just a tiny bit of play. Still my bike bogs when i go full throttle on low rpm. I saw that the idle/pilot jet was slightly damaged tho, On the top were you screw it. It's like a crack. It is btw a idle/pilot jet 45 (Original). Should i buy a new 45 or should i go higher? The next option that i have from 45 is 48. Btw it is a KTM 525sx from 2004. So it is the exact same carb.

[@tonyrichengod9280]

Very thorough video man. Thank you. Liked, saved, and subbed.

[@macwitt8788]

Mine 150r keeps dying even after this. Should I upgrade my leak jet?

[@canamxmr4760]

This video helped me a lot thank you. I have the accelerator pump dialed in; however, I still notice a slight bog here and there when just cracking the throttle... and sometimes a hanging idle. Would you suspect a pilot jet being too lean?

[@HTMR]

Hanging idle is lean. Adjust the fuel screw. If you get to 3 turns out, increase pilot jet size : kzbin.info/www/bejne/oYbaZWSpiraVirs

[@canamxmr4760]

@@HTMR thanks!!!! I am 3.5 turns out so I’m definitely lean. Appreciate the info!!!

[@RideRedFred]

HUGE THANKS.NOW MY BIKE RUNS AMAZING.👌🙏🙌

[@savila10]

sorry for the late post, great video, crf450x ap pump its working ok but squirt duration is too short, i have the o ring mod and the squirt timing is fine. how to improve squirt duration? bike bog on wot and then recover really hard.

[@HTMR]

Take a look at the rivet length on bottom of diaphragm. If you have a long rivet, you can grind it down to increase duration.

[@orvilleortiz8616]

I have a 06 trx450er with stage 2 hotcams,stock Ferrea Valves,100mm Athena Cylinder with CP Carillo piston and full Barkers exhaust,stock air filter no lid,the acc pump screw was moved around, so I'd like to ask your opinion on jetting and timing screw? Sea level is 105' thanks and great video brother!!!!

[@HTMR]

I can't recommend specific jets, as I never jetted your combo. First, start by tuning your pilot jet fuel screw per this video: howtomotorcyclerepair.com/how-to-4-stroke-mx-fuel-screw-adjustment-yzf-crf-kxf-rmz-fcr/

[@johnnygalvan1344]

Would a dirty fmf pipe or clogged pipe have anything to do with spark ?

[@victorwillemsens2368]

Thanks for the video, helps a lot. I have a Husqvarna SM610 (600cc) and my carb is Keihin FCR MX 41. Do you know if I change the OEM leak jet for the 45 size that you mentioned , it will works for me???

[@philheckman9165]

I have this same carb and I have up graded my 1990 Dr 350 and I want to put this carb on my 350, is there recommended jet size for this conversion?

[@darklol701]

Great, exactly what I need for my 09 yz250f. I'll try it tomorrow

[@explore-western-colorado970]

This trick fixed my issues thank you

[@charlesevenstad]

Fantastic video. Thank you for taking the time!

[@triumphtriumphant7352]

nice vid, i appreciate.i like it how you keep it simple and load it with info,you know other channels all seem scripted and have same old info repeated and sometimes more about the presenter.could you know a thing or two or anything about stators?especially winding lighting coil on to stock stator of a dirtbike?

[@HTMR]

There are companies that will add a lighting coil. It really depends on year make model and if there is room for one.

[@motorbikeryda883]

If the accelerator pump isn’t set up right could it cause the bike to hang revs once the throttle is blipped

[@tellenforelle]

Awesome video man! I am restoring a 02 DRZ 400e with the slant style FCR. Unfortunately this carb does not provide a screw to adust AP timing. However, there is a U shaped piece of metal that can be bent to adjust the AP lever up and down. I watched the video multiple times and adjusted the pump even more but i cant quite get it perfect. How can this be transferred to the slant carb?

[@HTMR]

I'm not familiar with that carb, however you have the right idea to bend the tab or modify the cam.

[@sandbiker]

Well done video. Probably the best one I've seen.

[@dannyboyrides4507]

everytime i squirt gas from that little nozle a get a very thin streak and doesnt seem powerful, ive chained the leak jet to a #35 and rejetted my main jet and pilot anf still does the same, what could the issue be? i have a bad bog (just like yours before the acc pump adjustment)

[@achupudasaini860]

Great video.. and i have a question regarding the tps. People say that disconnecting tps will reduce the throttle response and bike bogs but if i disconnect the tps and still setup the AP like you did will the bike still lack throttle response or there will be no any issues whatsoever with tps disconnected and AP working as it should. Please help me out.

[@HTMR]

Why disconnect the TPS? That is usually to control ignition curves.

[@achupudasaini860]

MatthewMCRepair thanks for replying. But the thing is i am installing this carb in a bike that has no tps connection provided and it actually have a stock carb which also doesnot have tps. It uses mikuni tm 34 style carburetor so i am upgrading it to a carb with an accelerator pump in it.

[@HTMR]

@@achupudasaini860 Gotcha.

[@EPstroker]

Great vid. Having a hard time figuring out a lean condition and decel popping on my crf 450x. Have to turn the fuel screw out more than 2.5 turns to make it run right without popping exaust or glowing header pipe. Pilot jet is a 60, main jet is a 175. Air box has been opened up and has a fmf pipe. Any advice on what to do to tune it so I can run the fuel screw 1.5 to 2 turns out without the exaust decel popping is welcomed.

[@HTMR]

You need to richen up the pilot jet. However you already are at a 60??? That is pretty big. Check for vacuum leaks and make sure hot start plunger is clean and operational.

[@Railroad_Boys]

I have the same bog on my sons 150 and when he tries to pin it just like you did in the video it bogs. The carb is jetted with the jd kit up to 3,000ft. Stock leak jet on a 150R is 60. What size leak jet would you recommend? Thanks🤙🏼

[@HTMR]

Not sure for that model. The JD kits are usually pretty complete and should resolve any bogging. I'd give them a call and see what they say.

[@blakewalston5405]

Thank you so much this made my day

[@riffraff8426]

Adjustable fuel air mixture screw for an FCR39 on a DRZ400. Is there one that will work in the very small void between the carb and the starter motor. I tried the flexible one but it doesn’t like to turn or adjust under the load of the bend. Is there a nurled finger adjusted mixture screw?

[@HTMR]

amzn.to/3mqlabJ

[@ernestot.8482]

Thanks really much for your video!! I gonna try to make this simple mods in my wr250f and kill the bad effect of the bike die when accelerating fast

[@HighGrade_FireBlade]

For best results, you should be performing this with the slide lifted 0.8mm. I use an appropriately sized bbq skewer to hold it open while performing the backlash adjustment.

[@HTMR]

I've read that in the manual. I guess they are assuming that if the idle screw is not adjusted to where it needs to be (lifting the slide) then you need to lift with rod. At the end of the day, you want minimal clearance/backlash for a quick shot.

[@stockcar4d]

mate....cheers for these vids....bloody awesome...keep it up...some of us get all the info needed...even with the lighting or whatever lol

[@HTMR]

Haha thanks for the compliments! I think the lighting was off only in the intro...but who watches that anyway, right?

[@nealpennington223]

I know this is an old video but I have a question, would a progressive throttle cable cam have a negative effect on adjusting the pumper?

[@HTMR]

No, a throttle cam simply changes the pull rate on cable and how the slide raises.

[@MrJasonfromcanada]

Very informative, any tips on what would cause a ktm 250 sxf with the fcr carb to be impossible to start after stalling it on the trails? It will hot start no problem if you shut the bike off with the kill switch, but won’t start or kick over after my kid stalls it on a log of root.

[@HTMR]

Does it improve with using the hot start lever?

[@MrJasonfromcanada]

MatthewMCRepair no it doesn’t, but I’m wondering if I’m kicking it wrong by twisting the throttle when trying to start it after it’s been stalled and over fueling it. My personal bike is a 300 2 stroke so I’m way more familiar with those style carbs that don’t pump fuel when the throttle is twisted. I am going to install a JD jet kit in the fcr carb and hope it’ll start a little easier.

[@MrJasonfromcanada]

I did check the valve clearance last night and they’re all within spec around .12mm so that rules out that possible issue

[@HTMR]

@@MrJasonfromcanada No throttle during starting on 4 stroke. The AP will add fuel making it difficult to start.

[@Pillemann328]

There is a "green" acceleration pump spring available, from KTM. It is from the SXS Parts catalogue. If I mind correctly, it is a stiffer spring, what enhances the volume of the squirt. What do you think about it? I can´t really find any informations about this, or reviews. Thank you for the good video!

[@HTMR]

Diaphragm spring or arm spring?

[@Pillemann328]

@@HTMR arm spring here is a link with the part number www.braeuer-shop.de/artikel.php?id=21676

[@DeadEnduro]

Hey Matt. How do you reset the tps if you removed it?

[@greecemonkey1313]

Thanl you so much for the valuable info you provide us !!!!

[@davidleeroth3359]

Straight to the point! Thanks Bro.

[@jamesyeager7784]

If I do the I ring mod would I need to rejet to a bigger size?

[@rdgsupafli]

Just did this to my carb on a 06 250x fixed most the bog issue I had once warmed up and ur going u couldn’t tell no more. Plus jd jet kit

[@GIXXE750R]

Great video !!it was very helpful in my wr450f.. Best regards from Argentina

[@AdventureswithQuillen]

2008 KTM 450 XC-F...JD jet kit with fat O-ring mod and acc pump spacer installed as instructed. Carb was set up according to factory specs (idle and acc pump). After adjusting fuel screw and idle, I still get the bog from idle if I grab a handful of throttle. Everywhere else is smooth. Uuuggghhhh any help is greatly appreciated. I'm leaning towards an acc pump adjustment.

[@HTMR]

Bogs on the stand or while riding? Turn choke on and then go ride it at slow roll, go full throttle, if bog goes away your pump shot is lean. How many turns out on fuel screw? What size pilot jet? Yes the timing needs to be correct to get proper shot.

[@AdventureswithQuillen]

@@HTMR only bogs at idle when you go full throttle. It's clean everywhere else. 185 main 42 pilot. I believe I'm around 2 turn out on fuel screw. When I'm riding it, it runs fine as long as I don't go full throttle from idle.

[@HTMR]

@@AdventureswithQuillen Just so you know, bogging on the stand is meaningless. If it bogs while hitting it from a slow roll, then it is probably lean. Double check timing which can be done with carb on bike. Remove side cover and adjust it. Report back.

[@AdventureswithQuillen]

@@HTMR in that case I'm good to go. No bog at all when riding unless I give it full throttle from idle.

[@milesmolloy5946]

Hey so is this on the outside of the carb? And also when I snap the throttle it will big will the accelerator pump fix it?

[@ហេងមុនិន្ទ]

Can I use 2003 yz450f fcr carburetor rebuild kit for 2003 wr450f fcr carburetor? Is it fit?

[@Doctors101]

Awesome vid! You sure have helped me understand. I seem to be having to much squirt. Was looking at the Boysen Quick Shot 3 accelerator pump cover with adjustable leak valve. Would you recommend? Thanks

[@HTMR]

First let me ask what year make model?

[@Doctors101]

It's a 2001 wr250f.

[@HTMR]

@@Doctors101 I would just install a 45 leak and oring. Total cost $10. Also make sure fuel screw and pilot jet are setup and you will have a bike that runs mint and save some money. Usually I install 1 larger size on pilot jet to net me 2.5 out on fuel screw.

[@josiahbennett6612]

I know this is an old video! But I have a question. My AP screw cannot be adjusted to the point of that little play, the screw becomes undone before that. What could my issue be if you have any idea? Thanks! Edit: maybe I am confusing the play with the total downward movement of the arm? The play would be very very subtle then?

[@HTMR]

Not sure, send me a video.

[@Fish4SupperHD]

you ever end figuring it out? seems like i have no play aswell

[@glitchseeker2128]

Thank you so much for helping with theese carburetors, sub for you!

[@ant88z]

brilliant video. i have a low to mid range bog the when i blast the throttle it goes away and pulls like a beast any ideas.

[@HTMR]

So if you stay in the throttle during a bog, the engine will eventually recover? What year make model?

[@ant88z]

+MatthewMCRepair ktm exc 250f 2011 thanks

[@omarmorales4769]

Hey man, love the videos, you just do an excelente job, I have a little issue with my new FCR33 carb, it idles good and when i accelerate from bottom to top (on neutral) it seems good, but when i go to ride, it stumbles at mid rpms (half throttle), it goes like ta...tatata...tata..tata..., Then I keep accelerating at full throttle and the stumble disappears, and runs ok on top of acceleration. I changed the needles and it keeps stumbling at mid acceleration. It only happens when I go to ride, but not on neutral. Please i'll appreciate your comments.

[@HTMR]

Same problem if you slowly roll from idle to WOT?

[@omarmorales4769]

@@HTMR i found that the little squirt is not working properly, it squirts bubles of air and fuel

[@holdenvapes7321]

Good leak jet size for fcr39mx for Drz400?????

[@iRideuWatch]

I don't have my bike in front of me where I am at the moment. Can this be done with the carb still on the bike?

[@HTMR]

Yes on most models

[@TheMadVector]

Do you think that the "perfect" setting we saw is a must-have for _all_ cases where such carbs are used? Furthermore makes this only sense on a 250cc, or is this thing suitable for any cc? The blue pump spring has not been mentioned by the way. Original is green, and it is weaker than the blue one, therefore the time of injection should be raised. This certainly affects the result alot I guess. I already ordered the blue spring, and will get a suitable o-ring, and won't try what you did before i applied it.. Just got and use a very well conditioned FCR 41 MX on KTM 640 Duke 2, with a more or less proper setup. And setting up that juicy pump.

[@HTMR]

Most of my experience is with 250f's, which are typically lean from the factory. I've also worked on some 450f's that are too rich from the factory. It all depends. I don't have experience setting one up for your model.

[@TheMadVector]

Ok, been at our local KTM Shop. Talked to the richly experienced "master" (is it said like that in english?). Owner, friendly boss and founder of that shop. That guy was driving successfully alot of mx races trough the 90s, and used these carbs as well. He did not agree with my idea of "de-lagging" the pump, because it would result in a forced injection with the whole amount, which shouldnt be useful. The adjustment of the green marked screw is for WHEN the pump starts to work, in correlation with the slider position. Adjusting the screw just to decrease any play of the whole system, just affects exactly that. The setup of what the pump is injecting pretty much depends on what Leakjet is used. I ordered two different sizes, and I will tell you what results i got. Actually, it is pretty much like I hit the gas .. short *boorp* at first, and then it starts to throttle gently. No push or "kick-off"-feeling, that needs serious adjustment. The pump injects too much i guess, or just at the wrong time. The idea is, to add that second screw, you surely read about it, and reduce the injection time from actually like 2 secs, to about 1.1 to 1.2. But on one hand ... I also have an MTX-L with Gauge on it .. and it seems really to become very lean when hitting the gas, but how the heck.? ... I will try your idea. Just to be sure. Maybe this simple "mod" makes many other works unnecessary. Blue spring is attached, no mentionable improvement so far.

[@HTMR]

The FCR carbs did not appear until 98' or so. You really need to find out if you are lean or rich on the pump shot in order to correct it. From a slow roll, whack the throttle hard and do not let off. If it bogs and does not recover, you are lean. If it is rich, the engine will recover after a few seconds. If it is rich, you need a spacer or diaphragm with a longer rivet, or mess around with the leak jet. You can also add the second screw to limit travel that you mentioned.

[@TheMadVector]

Yeah, wrong expression, i ment to say the guy has like 20 yrs experience, and alot of these years with fcr carbs. anyhow, was driving today. Whacked the throttle to full, AFR ratio blasts to 18+ and even up to 22.4 in some tests @ different rpm, which is literally air. Then AFR drops town to 9-10 and as the pump finishes it's job, it is at about 14+-. This means the 168 Main is probably a little bit too big... weird.. really weird. Gonna try a 165 or 162 if it's not raining tomorrow. I come to the conclusion that the o-ring mod really could help preventing emaciating the mix if throttle is hit instantly to full, you see it kind of like that too? Next thing, which really annoys me today.. Was driving a few hours today. My Bike died like 27 times on-road, because of totally not getting anymore fuel, after racing a few curves and hitting the gas genuinely. I think as I needed to go to "Reserve" on the petcock of the nearly empty tank, while messing around with setups on the carb, some dirt came inside. I did not notice anything of that when I was driving yesterday., and I fully fueled the tank as i wanted to take a ride tomorrow. Then this morning, I changed the needle from some weird OBDTP to the well-known and to 98% used OCEKR needle, as i was not very happy with the "bandwidth" of the OBDTP, which is not very common for a LC4 engine. But that problem won't have something to do with the needle, I guess. When i use full throttle for more like 3 curves, or overtaking a few cars, AFR blows up to 22.4, and the engine stops.. I then may could roll a little bit and maybe bring her back to life. Then driving with like 1/4 gas may keep er alive. There's a little sieve over the needle valve, if i remember correctly, need to take a look there, damn.. :( Another question, do you believe that airfilters made of foam (like TwinAir) have more airflow than a BMC filter made out of "paper" stuff?

[@HTMR]

I never had the chance to mess around with a wideband on a motocycle. What leak jet size are you using? Do you have it timed to squirt as early as possible?

[@kieronbrowne7881]

Do accelerator pump issues like the one in your video also cause hanging idle? thanks Kieron

[@HTMR]

Any "lean" condition can cause a hanging idle.

[@kieronbrowne7881]

Thank you. I’ve set the mixture screw in the recommended 1 3/4 turns out so I’m not to sure what’s happening?

[@HTMR]

@@kieronbrowne7881 Did you adjust while running or just what the manual says?

[@kieronbrowne7881]

@@HTMR Started with factory setting then tried adjusting when running.

[@kohln9582]

My gas stream is a lot longer in duration than the one in the video… yet still have a lean bog. Would that longer stream have any bad effects?

[@HTMR]

Yes, what year make model is it?

[@kohln9582]

@@HTMR 07’ crf 250x

[@HTMR]

@@kohln9582 What size leak jet do you have in there now?

[@renzoagallardo]

Hey man thanks for the video. I have been having an issue bogging so I tried to adjust the so after watching this. mine squirts fuel toward the middle and pretty much hits the needle and is weaker than yours. Any ideas?

[@HTMR]

What size leak jet do you have? I'm not sure if the nozzle can be persuaded by twisting it with some pliers.

[@renzoagallardo]

I have a r & d power bowl and run the leak jet at 50. I believe I have fixed the problem tho. I think the nozzle was clogged. took some fishing line and tried to push through the hole. tested it afterwards and got good results. It's running quite a bit better than before but still lean on the low end so I may try to jump from a 45 pilot to a 48

[@HTMR]

I have tuned a CRF250R with that R&D AP cover and ran the adjustment all the way in for max pump shot. You should try that as well. Don't jump up in pilot unless fuel screw is 2.5 out or more.

[@Karlan_]

I have a small bog issue on a ktm 660 lc4 with the fcr-mx carburator. The bike just bogs down for a very small moment when I give throttle fast. The bike works fine but it is verry anoying. It just feels like it hessitates for a momet at first but it works fine after that. Could it be a worn out accpump membrane? the bike is 11yrs old and has been standing for a while. I really like your videos its good help when trying to learn about carburators!

[@HTMR]

Is this a new issue or has it always bogged? If 11yrs old and sitting for a while, I'd take it apart and clean it before anything else.

[@Karlan_]

I dont know if it has had this issue before but as I just recently got it I dont know. I will start with a proper clean to se if it helps thank you!

[@Karlan_]

MatthewMCRepair its not really a bog its just a slight hesitation. it makes it dificult to slide around a bend and wheelie the bike. its like a small delay when i open the throttle fast.

[@Taikausko]

Hello Matthew! I have FCR 41 from KTM 560 SMR and installed it to my KTM 640 bike. The squirt duration is close to 3 seconds and im wondering if its normal or not... Few months ago i installed the carb to my bike without testing the AP first. Previously the squirt was weak and short, but it believe it was because of shit in the nozzle. Now it squirts like never before.

[@HTMR]

The duration needed will depend on a lot of variables: weight, gearing, size motor etc... So do you have any issues like bogging?

[@Taikausko]

@@HTMR I had 100km test ride and it seems to accelerate good. This carb is new to me, so i dont know how it should behave compared to my old CV carb. At idle when quickly twisting throttle only 1/4 or less, its bogging little bit. When riding, its not doing it.

[@HTMR]

@@Taikausko Idle bog test is meaningless. If it does not bog while riding, and responds well, then it should be good to go.

[@Roadified]

Awesome, thanks! I have this problem ond will fix it tomorrow!

[@ChrisGuthrie]

So with the idle screw.... i can find 0 info on how to set that up. Mine has been tampered with (by a desperate madman trying to get his bike to run right) and im fairly certain this is where my crazy bog I can not get rid of is coming from... yet have no idea how to set up the base idle like you mentioned. Any help... or useful link that may explain this process?

[@HTMR]

For idle, you just adjust the big black knob for it to idle at 1800 rpm.

[@wannabecarguy]

@@HTMR that's a nice looking squirt...lol

[@Co-SS]

excellent video. your a pro man.